By using the expression for the shear stress derived in BSL book

$,$

$$show that the shear force on a sphere spinning at a constant angular velocity in a Stokes

$$

$$flow$,$ is zero. This means that a neutrally buoyant sphere

$($

weight equal buoyancy force

$)$

$$that is made to spin in a Stokes

$$

$$flow$,$ will neither rise nor fall, nor translate in any preferential direction in the

$($

x

$-$

y

$)$

$$plane$.$